Treatment of films and foils of organic cellulose esters



Feb. 18, 1936. M. HAGEDORN ET AL 2,030,983

TREATMENT OF FILMS AND FOILS ORGANIC CELLULOSE ESTERS Filed oct. s, 1932 Patented Feb. 18, l

UNITED STATES PATENT OFFICE l TREATBIENT F FILMS AND FOILS 0F ORGANIC CELLULOSE ESTERS Max Hagedorn, Dessau in Anhalt, and Paul Mller, Dessau-Ziebigk, Germany, assignors to Agfa Ansco Corporation, Binghamton, N. Y., a corporation of New York Application October 3, 1932, Serial No. 636,074

Germany October 5, 1931 14 Claims.

jects will be seen from thedetailed specification.

following hereafter.

In the accompanying drawing there are shown foils embodying our invention. Fig. 1 shows a.

conventional exaggerated cross-sectional view of a foil made of a cellulose derivative and saponi-` ed on both faces. Fig. 2 shows a like view of a foil provided on one face with a photographic emulsion layer and saponifed on the other.

A preliminary treatment of a cellulose acetate film to which a photographic gelatine emulsionv is to be applied, consists in superiiciallysaponifying one of its faces, so that this face shall be -more or less completely regenerated to cellulose in order to ensure a good adhesion between thel film and the layerof'applied emulsion. 'Ihis treatment produces a certain `improvement of the mechanical properties of the film, but not one of practical importance, the elongation in waterv of thesaponified material being at the same time. considerably increased. -Elongation in water means the percentage increase in length of a strip of the lm immersed for one hour in water at `18 C.' t

According; to this invention lms and foils of considerably improved mechanicalproperties and a sensitiveness to water which is not greater than that of existing commercial films of cellulose derivatives, are obtained by conducting the saponifying treatment in a particular way which will more clearly result from the following examples. The treatment renders the lms suitable for use as photographic supports. l

Furthermore we have found that it is not necessary to carryv out the saponication before applying a photographic emulsion to the lm. The treatment is also applicable to photographic films vwhich are still sensitive to light, but we prefer to apply in this case'the treatment to those photographic films bearing a finished picture. It is surprising that the improvement of the mechanical properties of the film is not impaired by the presence of the photographic layer. 'I'he nished, that is to say the developed and fixed emulsion layer containing metallic silver is not injured by the treatment. In order to secure that the distances-of the perforation holes and their size remain unchanged, the saponification, washing and drying may performed under tension.

The invention applicable to films of a cellulose ester, mixed ester or vether-ester of an ali- '5 .phatc-carboxylicacid having up to 5 carbon atoms, thel film containing .a known softening agent, advantageously in an amount of more than per cent andpreferably in an amount of to 35 percent, calculated on the cellulose 10 derivative. The saponication -is performed with a solution of an alkali metal hydroxide or ammonium hydroxide which solution acts as a swelling agent for the film forming colloid, and is carried out rapidly in. about 21/2 to 15 minutes, 15 at ordinary temperature.

'Ihe solvent for the saponifying agent must be miscible with water and must not react with the hydroxide to be dissolved therein. Suitable solvents are, for instance, fnethanol, ethyl alcohol, dioxane and glycolmonomethylether which are all used in their aqueous solution. On acount of its lproperty of swelling the film forming colloid, the alkaline liquid penetrates rapidly into the film. The most suitable concentration of the saponifying solution with regard to the proportion of its constitue'nts can easily be determined byl a few experiments. When the saponifying treatment, which may be applied to one or both faces of the nlm, has penetrated to at least one sixth of the thickness of the film, it is interrupted and by a Washing liquid having no solvent action on the softening agent, the last residues of the alkaline liquid are removed from the film. In the washing operation also those parts which have been preventing the dissolution of the softening agent.

A mixture of alcohol and water has, for instance,

proved useful. In this case alcohol is the solvent for the hydroxide and the saponication products and Water, when added in a suitable amount prevents the dissolution of the softeningI agent.

- As softening agents all those that are known for organic cellulose derivatives are suitable, but

also resin, artificial resin or the like, provided that they are at least partially soluble in the saponifying liquid or are-rendered soluble by action of this liquid.

The fhn treated. according to the invention has liquids 40 good mechanical properties. It consists either d a layer ofsaponiiled cellulose derivative and a layer of non-saponined cellulose derivative, or of two outer layers of saponied cellulose derivative and an inner layer of non-saponied cellu- Example 3.-A nlm of cellulose trlacetate containing about 30 per cent of toluene sulfamide as softening agent. is saponied on both sides at 25' C. with a solution of 10 per cent strength of caustic soda in aqueous methanol (water methanol:

lose derivative. The layers are interjoined at 1: 1)

. Saponlilediiyer on both softening El n ati s es mnt Thickness Tenaclty Elongation n? am? Thickness Acetic acid Percent Kilo: Percent nt Before treatment 40 l 175 100 20. 0 Paci). 5 n Pcrmtz 3 Saponiiled ior 2% minutes--. lill-1m 130 23. 2 0. 72 25 i0 Before treatment 1 30 170 105 16. 0 0. o 62. 3 Baponiiied for 2% minutes..` 12)-130 144 18. 7 0. 59 13 8 4 minutes 13b-140 IZ) 27. 5 0. 87 17 l0* 6 minutes. lm 128 24. 9 0. 82 19 1l their contact surfaces withoutI formation of sharp boundaries so that the lm does not tend to split up. The saponied layer, amounting to at least one sixth of the thickness of the film, reveals the very strong action of the saponifying liquidfwhich considerably surpasses the superficial saponiflcaless than 1.5 per cent.

Thick agent ness Tummy tion Before treatment--.... Treetedforlo minutes- Percent 10,8

Percent Kilos as n4 After the saponication the film is washed for about 3 minutes with diluted acetic acid of 3 per cent strength and then for 15 minutes with an aqueous solution of methanol of 50 per cent strength. After treatment the lm has a content of softening agent of about 10.4 per cent.

Example 2.--A lm of cellulose triacetate containing about 25 per cent of urea-formaldehyde resin as softening agent, is treated at 25 C. with a solution of 10 per cent strength of caustic soda in aqueous methanol (water: methanol=1 1).

` 'Elo softening Thlck- Elongatreat- Percent Kilo Percent .Percent Belfilgt- 29 u 125 105 12. 0 0. 38 meg... 12 11o-izo las 16.1 0.31

After the saponiilcation the iiim is washed for about 3 minutes with diluted acetic acid of 3 per cent strength and then for 15 minutes with an aqueous solution of methanol of 50 per cent strength. After treatment the lm has a con- ?5 tent of softening agent of about 12 per cent.

After the saponiflcation the lm is washed for about 3 minutes with diluted acetic acid of 3` per cent strength and then for 15 minutes with an aqueous, solution of methanol of 50 per cent strength. After treatment the 111m has a' content of softening agent of about. 14.3 per cent.

Example 4.-A 111m of hydrolized cellulose acetate (56.7 per cent of acetic acid) containing 24 per cent of toluene sulfonamide and 6 per cent of diethyl phthalate is saponiied at 24 C. for 5 minutes in a caustic potash solution of 9 per cent strength (water methanol=l:4).

F" t a n n t e s et s S t E* Eg E 2 .9. 22e: a e n n a p Kilos Percent VPercent p Before treatmente.-. 150 78 28.3 0.75 Alter treetmenth- 129 112 32. 5 l. 00 50 After thesaponiflcation the is washed for about 3 minutes with diluted acetic acid of about 3 per cent strength and then for 15 minutes with an aqueous solution of`metha`nol containing 60 percentof methanol. After treatment the lm tion of 10 per cent strength:

n g f es t s s c5 a u Cl l. '3 g1g .si ou s A 2 Se a e #l e p Kilos Percent Percent n Before treetlnent. 150 75 27.5 0.5

.uw trment.--.. 13o 4los a5. o o. 95 4o After the saponiflcation the film is washed for about 3 minutes with diluted acetic acid oi?v 3 per cent strength and then for 15 minutes with an aqueous solution of methanol of 50 percent strength. Y

Example 6.-A lm of oxyethylcellulose acetate containing 30 per cent of ethyl aoetanillde is saponied at 23 C. for 8 minutes in a caustic soda solution (Water :'methanol=1:1) of 10 per cent strength.

0 E .E '2 u u n :i u g 'a B QU d' n h c, E s s .e sse El E' Bl lil El p Kilos Percent Percent p Before treatment.- 150 73 25. 0 0. 60 Aitor treatmant---- 120 100 28. 0 0. 85 35 After the saponication the film is washed for about 3 minutes with diluted acetic acid of about 3 per cent strength and then for 15 minutes with an aqueous solution of methanol containing 60 per cent of methanol.

Example 7.-A foil of cellulose triacetate containing 40 per cent of p-toluene sulfonamide is saponiiied for 15 minutes at 24 C. on one face.

with a caustic soda solution of per cent strength in equal parts of water and methanol.

After the saponiiicatlon the lm is washed for about 3 minutes with diluted acetic acid of 3 per cent strength and then for minutes with an aqueous solution of methanol of 50 per cent strength. After treatment the film has a content of softening agent of about 15.5 per cent.

Our invention is not limited to the foregoing examples nor to the specific details given therein. lI'he best modification of operating the treatment will be found in each case by a few experiments. Though a solution of caustic soda in aqueous methanol, as disclosed in the examples, has proved to be well suitable other hydroxides and other solvents adapted to dissolve the hydroxide and the softening agent contained in the lm are suitable. 'We contemplate as included within our invention all such modications as fall Within the scope of the appended claims. The term sheet as used in the claims is intended to include foils of cellulose derivatives and photographic films, such as have not yet been exposed and such as have been nished by developing and fixing.

What we claim is:

1. A process which comprises treating a sheet made of a cellulose derivative selected from the group consisting of cellulose esters, mixed esters.

and ether-esters of an aliphatic carboxylic acid having up to 5 carbon atoms and containing a softening agent with a solution of a hydroxide selected from the group consisting of alkali metal hydroxides and ammonium hydroxide in a liquid which has a swellingaction on the lm forming colloid, and removing from the sheet the treating liquid by means of liquid which has no solvent action on the softening agent.

2. A process which comprises treating a sheet made of a cellulose derivative selected from the group consisting of cellulose esters, mixed esters and ether-esters of an aliphatic carboxylic acid having up to 5 carbon atoms and containing at A least 15 per cent of softening agent with a solulwhich has no-solvent action on the softening' agent.

3. A process which comprises treating a sheet made of a cellulose derivative selected from the group consisting 'of cellulose acetate, cellulose acetate-butyrate and oxyethylcellulose acetate and containing at least 15 percent of softening agent with a solution of a. hydroxide selected from the group consisting of alkali metal hydroxides and ammonium hydroxide in a liquid which has a swelling action on the illm forming colloid, and removing from thessheet the treating liquid by means of liquid which has no solvent action on the softening agent.

4. A process which comprises treating a sheet made'of a cellulose derivative selected from the group consisting of cellulose acetate, cellulose acetate-butyrate and oxyethylcellulose acetate and containing about to 35 per cent of softening agent with a solution of a hydroxide selected from the group consisting of alkali metal hydroxides and ammonium hydroxide in a liquid which has a swellingaction on the lm forming colloid, and removing from the sheet the treating liquid by means of liquid which has no solvent action on the softening agent.

5. A process which comprises treating a sheet made of a cellulose derivative selected from the group consisting of cellulose acetate, cellulose acetate-butyrate and oxyethylcellulose acetate and containing about 25 to 35 per cent of a softening agent at least partly soluble in aqueous methanol witha solution of caustic soda 'in aqueous methanol, and removing from the sheet the treating liquid by means of 'liquid which has no solvent action on the softening agent.

6. A'process which comprises treating a sheet made of a cellulose derivative selected from the group consisting of cellulose acetate, cellulose acetate-butyrate and oxyethylcellulose acetate and containing about 25 to 35 per cent of a softening agent at least partly soluble in aqueous methanol with a solution of caustic soda in aqueous methanol of about 50 per cent strength, and removing from the sheet the treating liquid by means of liquid which has no solvent action on the softening agent.

7. A process which comprises treating a sheet made of a cellulose derivative selected from the group consisting of cellulose acetate, cellulose acetate-butyrate and oxyethyl-cellulose acetate and containing about 25 to 35 per cent of a softening agent at least partly soluble in aqueous methanol but insoluble in aqueous ethanol with a solution of caustic soda in aqueous methanol of about 50 per cent strength, and removing from the sheet the treating liquid by means of an aqueous solution of ethanol.

8. A process which comprises treating a sheet made of cellulose triacetate and containing about 25 to 35 per cent oi' a softening agent at least partly soluble in aqueous methanol but insoluble in aqueous ethanol with a solution of caustic soda in aqueous methanol of about 50 per cent strength, and removing from the sheet the treating liquid by means of an aqueous solution of ethanol.

9. A process which comprises' treating a sheet made of cellulose acetate containing about 52 to 57 per cent of acetic acid and containing about 25 to 35 per cent of a softening-agent at least partly soluble in aqueous methanol but insoluble in aqueous ethanol with a solution of caustic soda in aqueous methanol of about 50 per cent strength, and removing from the sheet the treating liquid by means of an aqueous solution of ethanol.

10. A sheet Vmade of a cellulose derivative selected from the group consisting of cellulose esters, mixed esters and ether-esters of an aliphatic carboxylic acid having up to carbon atoms and containing a softening agent, said sheetbeing on at least one of itsfaces saponiiied to the extent of at least one-sixth of its thickness by treatment with a -saponifying solution having a swelling action on the lm forming colloid and v 'having an elongation in water of less than 1.5

percent. .Y

1l. A sheet made of a cellulose derivative selected from the group consisting of cellulose acetate, cellulose 'acetate-butyrate and oxyethylcellulose acetate and containing `a. softening agent, said sheet being on at least one of its faces saponiiied to-the extent of at least one-sixth of with a saponifying solution having a swelling action on the lm forming colloid and having an elongation in water of less than.1.5 per cent. l

13. A sheet made of cellulose acetate containing about 52 to 57 per cent of acetic acid and containing a softening agent, said sheet being on at least one of its faces saponified to the extent of atleast one-sixth of its thickness by treatmenty with a saponifying solution Ahaving a swelling action on the nlm forming'colloid and having an elongation in water of less than 1.5 percent.

14. A .process which comprises treating a' sheet made of a cellulose derivative selected from the group consisting of cellulose esters, mixed esters and ether-esters oi.` an aliphatic vcarboxylic acid having up to 5 carbon atoms and containing a softening agent with a solution of a. hydroxide selected from the group consisting of alkali metal hydroxides and ammonium hydroxide in a liquid which has a swelling action on the lm forming colloid and which is selected from the group consistimz of an aqueous v'solution of methanol, ethyl alcohol, dioxane and glycolv monoethyl ether and removing from the sheet the treating liquid `by means of liquid which has no solvent action on the softening agent.

MAX HAnGEDORN.

PAUL MOLLER. 

